Metal azo pigments

ABSTRACT

The novel yellow metal azo pigments based on at least two metal azo compounds which differ a least in the type of metal have improved color strengths and are of excellent suitability for pigmentation of pigment preparations for a broad field of use.

The present invention relates to novel yellow metal azo pigments based on at least two metal azo compounds which differ at least in the type of metal, to processes for production thereof and to the use thereof as yellow pigment in pigment preparations.

BACKGROUND INFORMATION

The preparation of metal complexes from azobarbituric acid with nickel salts and the use thereof as yellow pigments has long been known and has been described many times in the literature (cf., for example, W. Herbst, K. Hunger: Industrial Organic Pigments, 3rd edition 2004, p. 390/397). It is additionally known that these products can be reacted further, for example with melamine or melamine derivatives, in order to improve the performance properties of the pigments, for example in the colouring of plastics, lacquers and colour filters for LCDs.

In addition, literature states that colouristic properties can also be adjusted using, apart from nickel salts, one or more salts of different metals as well. The application EP-A 1 591 489 describes metal complexes of azo compounds containing, as metals, those from the group of the alkali metals, alkaline earth metals, the lanthanoids, and aluminium, scandium, titanium, vanadium, chromium, manganese, cobalt, copper, nickel and zinc, and optionally iron. The pigments obtained have a different colour locus compared to the pure nickel-azobarbituric acid complexes.

Controlled surface coverage of the metal azo pigment can likewise achieve an improvement in performance-based properties, specifically the lowering of the dispersion hardness as a measure of the dispersion properties of the pigment. However, this method of improving dispersibility is associated with a reduction in the colour intensity of the pigment, which is directly dependent on the concentration of covering agent.

A further means of adjusting performance-based properties is to subject the pigments produced from nickel-azobarbituric acid complexes with melamine, for example, to a heat treatment. This process step is associated with a controlled alteration in the particle size of the pigments and the specific surface area thereof. This process is described, for example, in EPA 0 994 162.

However, the metal azo pigments known from the prior art are still in need of improvement with regard to the performance properties thereof.

SUMMARY OF THE INVENTION

It has been found that metal azo pigments based on azobarbituric acid, nickel salts and melamine and/or melamine derivatives and at least one further lanthanoid salt surprisingly have improved colour strengths. The improvement of these properties enables improved use of these products, inter alia, for colouring of plastics and lacquers, and for use in inkjets and as a component of colour filters for LCDs.

DETAILED DESCRIPTION OF THE INVENTION

The invention therefore relates to metal azo pigments, characterized in that they comprise the following components:

-   a) at least two metal azo compounds which differ at least in the     type of metal and which each contain     -   structural units of the formula (I), or the tautomeric forms         thereof,

-   -   in which     -   R¹ and R² are each independently OH, NH₂ or NHR⁵,     -   R³ and R⁴ are each independently ═O or ═NR⁵,     -   R⁶ is hydrogen or alkyl, preferably C₁-C₄-alkyl, and     -   Ni²⁺ metal ions and/or one or more metal ions Me¹ and optionally         one or more metal ions Me²,         -   where         -   Me¹ is a metal ion selected from the group of La³⁺, Ce³⁺,             Pr³⁺, Nd³⁺, Nd³⁺, Sm²⁺, Sm³⁺, Eu³⁺, Eu³⁺, Gd³⁺, Tb³⁺, Dy³⁺,             Ho³⁺, Er³⁺, Tm³⁺, Yb²⁺ and Yb³⁺,         -   and         -   Me² is a metal ion selected from the group of         -   Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Sc³⁺, Y³⁺, Ti²⁺, Ti³⁺, Zr²⁺, Zr³⁺,             V²⁺, V³⁺, Nb³⁺, Cr³⁺, Mo²⁺, Mo³⁺, Mn²⁺, Fe²⁺, Fe³⁺, Co²⁺,             Co³⁺, Cu²⁺, Zn²⁺, Cd²⁺, Al³⁺ and Pb²⁺,         -   with the proviso that the amount of Ni²⁺ metal ions and             metal ions from the Me¹ group together is 95 to 100 mol %             and the amount of metal ions from the Me² group is 0 to 5             mol %, based in each case on one mole of all metal ions in             the metal azo pigment,     -   and     -   where the molar ratio of Ni²⁺ metal ions to Me¹ metal ions in         the metal azo pigment is 1:1 to 19:1, preferably 2:1 to 4:1 and         more preferably 2.3:1 to 3:1,     -   and

-   b) at least one compound of the formula (II)

-   -   in which     -   R⁶ is hydrogen or alkyl, preferably C₁-C₄-alkyl optionally mono-         or polysubstituted by OH.

Preferably, in formula (I), R¹ and R² are each independently OH, NH₂ or NHR⁵ where R⁵ is hydrogen or C₁-C₄-alkyl,

Preferably, in formula (I), R³ and R⁴ are each independently ═O or ═NR⁵ where R⁵ is hydrogen or C₁-C₄-alkyl.

More preferably, in formula (I), R¹ and R² are OH and R³ and R⁴ are ═O.

Preferably, in formula (II), R⁶ is hydrogen or C₁-C₄alkyl optionally mono- or polysubstituted by OH. More preferably, in formula (II), R⁶ is hydrogen.

Based on one mole of all metal ions present in the metal azo pigment, the amount of Ni²⁺ and Me¹ metal ions together is generally 95 to 100 mol % and the amount of metal ions Me² 0 to 5 mol %; the amount of Ni²⁺ and Me¹ metal ions together is preferably 98 to 100 mol % and the amount of metal one Me² 0 to 2 mol %, and the amount of Ni²⁺ and Me¹ metal ions together is more preferably 99.9 to 100 mol % and the amount of metal ions Me² 0 to 0.1 mol %.

In general, the molar ratio of Ni²⁺ to Me¹ metal one in the meta azo pigment is 1:1 to 19:1, preferably 2:1 to 4:1 and more preferably 2.3:1 to 3:1.

Substituents in the definition of alkyl denote, for example, straight-chain or branched C₁-C₆-alkyl, preferably straight-chain or branched C₁-C₄-alkyl, which may optionally be mono- or polysubstituted identically or differently, for example by halogen such as chlorine, bromine or fluorine: —OH, —CN, —NH₂ or C₁-C₆-alkoxy.

The metal ions Me¹ and Me² are preferably in their most stable oxidation states.

Me¹ is generally a metal on selected from the group of La³⁺, Ce³⁺, Pr³⁺, Nd²⁺, Nd³⁺, Sm²⁺, Sm³⁺, Eu²⁺, Eu³⁺, Gd³⁺, Tb³⁺, Dy³⁺, Ho³⁺, Er³⁺, Tm³⁺, Yb²⁺ and Yb³⁺. Preferably, Me¹ is a metal ion selected from the group of La³⁺, Ce³⁺, Pr³⁺, Nd³⁺, Sm³⁺, Eu³⁺, Gd³⁺, Tb³⁺, Dy³⁺, Ho³⁺, Er³⁺, Tm³⁺ and Yb³⁺, and most preferably from the group of La³⁺, Ce³⁺, Pr³⁺, Nd³⁺, Sm³⁺, Tb³⁺ and Ho³⁺.

Me² is generally a metal ion selected from the group of Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Sc³⁺, Y³⁺, Ti²⁺, Ti³⁺, Zr²⁺, Zr³⁺, V²⁺, V³⁺, Nb³⁺, Cr³⁺, Mo²⁺, Mo³⁺, Mn²⁺, Fe²⁺, Fe³⁺, Co²⁺, Co³⁺, Cu²⁺, Zn²⁺, Cd²⁺, Al³⁺ and Pb²⁺.

Preferably, Me² is a metal ion selected from the group of Mg²⁺, Ca²⁺, Sr²⁺, Y³⁺, Mn²⁺, Fe²⁺, Fe³⁺, Co²⁺, Co³⁺, Cu²⁺, Zn², Al³⁺, and more preferably from the group of Sr²⁺, Fe²⁺, Fe³⁺, Co²⁺, Co³⁺, Cu²⁺, Zn²⁺ and Al³⁺.

In the case that the metal azo compounds of component a) contain divalent metal ions Me from the group Me¹ and Me², the structural units of the formula (I) and the metal ions Me can be regarded as compounds of the formula (Ia)

However, it is also possible that the metal ion is bonded via the nitrogen atoms in a tautomeric notation of the formula (Ia).

The same formula representation can also be applied to the structural units of the formula (I) with the Ni²⁺ metal ions. This representation serves merely for illustration and does not make any claim to scientific correctness.

In the case of trivalent metal ions Me¹ and Me², the charge is balanced by an equivalent amount of anionic structural units of the formula (I).

Preferably, said charge of the doubly negatively charged structural units of the formula (I) is balanced to an extent of 80% to 100%, more preferably to an extent of 95% to 100% and most preferably to an extent of 99.9% to 100% by the sum total of all Ni²⁺ and Me¹ metal ions present in the metal azo pigment and any further metal ions Me².

Preferably, said metal azo compounds of components a) form adducts with components b), i.e. the compounds of the formula (II).

Adducts are understood to mean molecular assemblies in general. The bond between the molecules here may be the result, for example, of intermolecular interactions or Lewis acid-base interactions or of coordinate bonds.

The term “adduct” in the context of the present invention shall generally encompass all kinds of intercalation and addition compounds.

The terms “intercalation compound” or “addition compound” in the context of the present invention shall be understood, for example, to mean compounds which are formed on the basis of intermolecular interactions such as van der Waals interactions or else Lewis acid-base interactions. The way in which the intercalation proceeds here depends both on the chemical properties of the component to be intercalated and on the chemical nature of the host lattice. Compounds of this kind are frequently also referred to as intercalation compounds. In a chemical sense, this is understood to mean the intercalation of molecules and ions (less commonly atoms as well) into chemical compounds.

This shall additionally also be understood to mean inclusion compounds called clathrates. These are compounds of two substances, one of which is a guest molecule intercalated into a lattice or cage composed of a host molecule.

The terms “intercalation compound” or “addition compound” in the context of the present invention shall also be understood to mean mixed intercalation crystals (including interstitial compounds). These are chemical non-stoichiometric crystalline compounds composed of at least two elements.

In addition, the terms “intercalation compound” or “addition compound” in the context of the present invention shall also be understood to mean compounds which are formed on the basis of coordinate bonds or complex bonds. Compounds of this kind refer, for example, to mixed substitution crystals or mixed replacement crystals in which at least two substances form a common crystal and the atoms of the second component are at regular lattice sites of the first component.

Preference is given to metal azo pigments comprising the adducts of

-   -   a) at least two metal azo compounds which differ at least in the         type of metal and which each contain structural units of the         above-specified formula (I)         -   in which R¹ and R² are OH,         -   and         -   R³ and R⁴ are ═O,         -   and         -   Ni²⁺ metal ions and/or one or more metal ions Me¹ and             optionally one or more metal ions Me²,         -   where         -   Me¹ is a metal ion selected from the group of La³⁺, Ce³⁺,             Pr³⁺, Nd²⁺, Nd³⁺, Sm²⁺, Sm³⁺, Eu²⁺, Eu³⁺, Gd³⁺, Tb³⁺, Dy³⁺,             Ho³⁺, Er³⁺, Tm³⁺, Yb²⁺ and Yb³⁺, more preferably from the             group of La³⁺, Ce³⁺, Pr³⁺, Nd³⁺, Sm³⁺, Eu³⁺, Gd³⁺, Tb³⁺,             Dy³⁺, Ho³⁺, Er³⁺, Tm³⁺ and Yb³⁺, and most preferably from             the group of La³⁺, Ce³⁺, Pr³⁺, Nd³⁺, Sm³⁺, Tb³⁺ and Ho³⁺,         -   and         -   Me² is a metal ion selected from the group of Mg²⁺, Ca²⁺,             Sr²⁺, Ba²⁺, Sc³⁺, Y³⁺, Ti²⁺, Ti³⁺, Zr²⁺, Zr³⁺, V²⁺, V³⁺,             Nb³⁺, Cr³⁺, Mo²⁺, Mo³⁺, Mn²⁺, Fe²⁺, Fe³⁺, Co²⁺, Co³⁺, Cu²⁺,             Zn²⁺, Cd²⁺, Al³⁺ and Pb²⁺, more preferably from the group of             Mg²⁺, Ca²⁺, Sr²⁺, Y³⁺, Mn²⁺, Fe²⁺, Fe³⁺, Co²⁺, Co³⁺, Cu²⁺,             Zn², Al³⁺, and more preferably from the group of Sr²⁺, Fe²⁺,             Fe³⁺, Co²⁺, Co³⁺, Cu²⁺, Zn²⁺ and Al³⁺,         -   with the proviso that the amount of Ni²⁺ metal ions and             metal ions from the Me¹ group together is 95 to 100 mol %             and the amount of metal ions from the Me² group is 0 to 5             mol %, based in each case on one mole of all metal ions in             the metal azo pigment,         -   and         -   where the molar ratio of Ni²⁺ metal ions to Me¹ metal ions             in the metal azo pigment is 1:1 to 19:1, preferably 2:1 to             4:1 and more preferably 2.3:1 to 3:1,         -   and         -   b) at least one compound of the above-specified formula (II)         -   in which         -   R⁶ is hydrogen.

Particular preference is given to metal azo pigments comprising the adducts of

-   -   a) at least two metal azo compounds which differ at least in the         type of metal and which each contain structural units of the         above-specified formula (I)         -   in which         -   R¹, R², R³, R⁴ and R⁵ have the above-specified general and             preferred definition,         -   and         -   contain Ni²⁺ ions and/or one or more metal ions Me¹,         -   where         -   Me¹ is a metal ion selected from the group of La³⁺, Ce³⁺,             Pr³⁺, Nd²⁺, Nd³⁺, Sm²⁺, Sm³⁺, Eu²⁺, Eu³⁺, Gd³⁺, Tb³⁺, Dy³⁺,             Ho³⁺, Er³⁺, Tm³⁺, Yb²⁺ and Yb³⁺, preferably a metal ion             selected from the group of La³⁺, Ce³⁺, Pr³⁺, Nd³⁺, Sm³⁺,             Eu³⁺, Gd³⁺, Tb³⁺, Dy³⁺, Ho³⁺, Er³⁺, Tm³⁺ and Yb³⁺, and more             preferably from the group of La³⁺, Ce³⁺, Pr³⁺, Nd³⁺, Sm³⁺,             Tb³⁺ and Ho³⁺,         -   with the proviso that the amount of Ni²⁺ ions and metal ions             from the Me¹ group is 100 mol %, based on one mole of all             metal ions in the metal azo pigment,         -   and         -   where the molar ratio of Ni²⁺ metal ions to Me¹ metal ions             in the metal azo pigment is 1:1 to 19:1, preferably 2:1 to             4:1 and more preferably 2.3:1 to 3:1,         -   and     -   b) at least one compound of the above-specified formula (II) in         which     -   R⁵ has the above-specified general and preferred definitions.

Compounds suitable for forming an adduct in the sense of the above definition with the metal azo compounds of component a) may be either organic or inorganic compounds. These compounds are referred to hereinafter as adduct formers.

Adduct formers suitable in principle come from an extremely wide variety of different compound classes. For purely practical reasons, preference is given to those compounds which are solid or liquid under standard conditions (25° C., 1 bar).

Among the liquid substances, preference is generally given to those having a boiling point of 100° C. or higher, preferably of greater than or equal to 150° C. at 1 bar. Suitable adduct formers are generally acyclic and cyclic organic compounds, for example aliphatic and aromatic hydrocarbons which may be substituted, for example, by OH, COOH, NH₂, substituted NH₂, CONH₂, substituted CONH₂, SO₂NH₂, substituted SO₂NH₂, SO₃H, halogen, NO₂, CN, —SO₂-alkyl, —SO₂-aryl, —O-alkyl, —O-aryl, —O-acyl.

Carboxamides and sulphonamides are a preferred group of adduct formers; also especially suitable are urea and substituted ureas such as phenylurea, dodecylurea and others, and the polycondensates thereof with aldehydes, especially formaldehyde; heterocycles such as barbituric acid, benzimidazolone, benzimidazolone-5-sulphonic acid, 2,3-dihydroxyquinoxaline, 2,3-dihydroxyquinoxaline-6-sulphonic acid, carbazole, carbazole-3,6-disulphonic acid, 2-hydroxyquinoline, 2,4-dihydroxyquinoline, caprolactam, melamine, 6-phenyl-1,3,5-triazine-2,4-diamine, 6-methyl-1,35-triazine-2,4-diamine, cyanuric acid.

Likewise suitable in principle as adduct formers are polymers, preferably water-soluble polymers, for example ethylene-propylene oxide block polymers, preferably having an M_(n) greater than or equal to 1000, especially from 1000 to 10 000 g/mol, polyvinyl alcohol, poly(meth)acrylic acids, modified cellulose such as carboxymethyl celluloses, hydroxyethyl and -propyl celluloses, methyl and ethyl hydroxyethyl celluloses.

According to the invention, the adduct formers used are those of the formula (II). Especially preferred here is melamine.

In general, the metal azo pigments of the invention contain 0.05 to 4 mol, preferably 0.5 to 2.5 mol and most preferably 1.0 to 2.0 mol of compounds of the formula (II) per mole of structural units of the formula (I).

The metal azo pigments of the invention preferably have a specific surface area (m²/g) of 20 to 200 m²/g, especially 60 to 160 m²/g, most preferably 90 to 130 m²/g. The surface area is determined in accordance with DIN 66131: determination of the specific surface area of solids by gas adsorption according to Brunauer, Emmett and Teller (B.E.T).

The metal azo pigments of the invention may be physical mixtures or chemical mixed compounds. Preferably, the physical mixtures are mixtures of adducts of said metal azo compounds of component a) and the compounds of the formula (II) of component b) which differ at least in terms of the type of metals. Preferred examples are the physical mixture of the adducts of a1) the pure Ni azo compound with b1) melamine and the adducts of a2) one or more Me¹ azo compounds with b2) melamine and optionally the adducts of a3) with one or more Me² azo compounds with b3) melamine. The chemical mixed compounds are, for example and with preference, adducts of metal azo compounds of component a) with compounds of the formula (II) of component b), preferably melamine, where the Ni²⁺ and Me¹ metal ions, and any further metal ion Me², are incorporated into a common crystal lattice.

The metal azo pigments of the invention can be prepared by reacting alkali metal salts of the formula (III), or tautomers thereof, preferably the sodium or potassium salts, in the presence of at least one compound of the formula (II), with nickel salts and one or more Me¹ salts and optionally one or more Me² salts.

In the context of the present invention, Me¹ salts are understood to mean salts of the di- or trivalent metals lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, ytterbium, erbium, thulium, more preferably the di- or trivalent metals lanthanum, cerium, praseodymium, neodymium, samarium, terbium and holmium.

In the context of the present invention, Me² salts are understood to mean salts of the di- or trivalent metals zinc, copper, aluminium, iron, cobalt, magnesium, calcium, strontium, manganese, yttrium, scandium, titanium, niobium, molybdenum, vanadium, zirconium, cadmium, chromium, lead and barium, preferably zinc, copper, aluminium, iron, cobalt, magnesium, calcium, strontium, manganese and yttrium and more preferably zinc, copper, aluminium, iron, cobalt and strontium.

The metal azo pigments of the invention can also be prepared by mixing the adducts of a1) metal azo compounds containing structural units of the formula (I) and Ni²⁺ metal ions and b1) compounds of the formula (II) with adducts of a2) metal azo compounds containing structural units of the formula (I) and one or more metal ions Me¹ and b2) compounds of formula (II), optionally with adducts a3) of metal azo compounds containing structural units of the formula (I) and one or more metal ions Me² and b3) compounds of the formula (II).

The present invention further provides a process for producing the metal azo pigments of the invention, which is characterized in that at least one compound of the formula (III), or tautomers thereof,

-   -   in which     -   X is an alkali metal ion, preferably a sodium or potassium ion,     -   R¹ and R² are each independently OH, NH₂ or NHR⁵,     -   R³ and R⁴ are each independently ═O or ═NR⁵,     -   and     -   R⁵ is hydrogen or alkyl, preferably C₁-C₄-alkyl,         in the presence of at least one compound of the formula (II), is         reacted simultaneously or successively with at least one nickel         salt and at least one further Me¹ metal salt from the group of         the di- or trivalent La³⁺, Ce³⁺, Pr³⁺, Nd²⁺, Nd³⁺, Sm²⁺, Sm³⁺,         Eu²⁺, Eu³⁺, Gd³⁺, Tb³⁺, Dy³⁺, Ho³⁺, Er³⁺, Tm³⁺, Yb²⁺ and Yb³⁺         salts, preferably from the group of the La³⁺, Ce³⁺, Pr³⁺, Nd³⁺,         Sm³⁺, Eu³⁺, Gd³⁺, Tb³⁺, Dy³⁺, Ho³⁺, Tm³⁺ and Yb³⁺ salts and more         preferably from the group of the La³⁺, Ce³⁺, Pr³⁺, Nd³⁺, Sm³⁺,         Tb³⁺, and Ho³⁺ salts and optionally with one or more Me² metal         salts from the group of the Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Sc³⁺, Y²⁺,         Ti²⁺, Ti³⁺, Zr²⁺, Zr³⁺, V²⁺, V³⁺, Nb³⁺, Cr³⁺, Mo²⁺, Mo³⁺, Mn²⁺,         Fe²⁺, Fe³⁺, Co²⁺, Co³⁺, Cu²⁺, Zn²⁺, Cd²⁺, Al³⁺ and Pb²⁺ salts,         preferably from the group of the Mg²⁺, Ca²⁺, Sr²⁺, Y³⁺, Mn²⁺,         Fe²⁺, Fe³⁺, Co²⁺, Co³⁺, Cu²⁺, Zn², Al³⁺ salts and more         preferably from the group of the Sr²⁺, Fe²⁺, Fe³⁺, Co²⁺, Co³⁺,         Cu²⁺, Zn²⁺ and Al³⁺ salts, where 0.5 to 0.95 mol of at least one         nickel salt, 0.05 to 0.5 mol of at least one Me¹ salt and 0.05         to 0 mol of at least one Me² salt are used per mole of compound         of the formula (III), and where the sum total of the molar         amounts of the metal salts used together is one mole.         Preferably, 0.66 to 0.80 mol of at least one nickel salt and         0.20 to 0.33 mol of at least one Me¹ salt are used per mole of         compound of the formula (III).

Most preferably, 0.70 to 0.75 mol of at least one nickel salt and 0.25 to 0.30 mol of at least one Me¹ salt are used per mole of compound of the formula (III).

In general, the process of the invention is performed using 0.05 to 4 mol, preferably 0.5 to 2.5 mol and most preferably 1.0 to 2.0 mol of compound of the formula (II) per mole of compound of the formula (III).

Alternatively, for the preparation, instead of the di-alkali metal compound of the formula (III), it is also possible to use a mono-alkali metal compound of the formula (IIIa), or tautomers thereof,

-   -   in which X, R¹, R², R³ and R⁴ have the definition given for         formula (III),         or a mixture of compounds of the formula (III) and (IIIa). The         stated molar amounts of nickel and Me¹ salts and any Me² salts         to be used and of compounds of the formula (II) in these cases         relate to the sum total of the molar amounts of the         compounds (III) and (IIIa) used.

Especially preferred is the preparation of binary nickel/Me¹ azobarbituric acid-melamine adducts.

The process of the invention is generally conducted at a temperature of 60 to 95° C. in aqueous solution at a pH below 7. The zinc and copper salts for use in accordance with the invention and any further metal salts to be used can be used individually or as a mixture with one another, preferably in the form of an aqueous solution. The compounds of the formula (II) may likewise be added individually or as a mixture with one another, preferably in the form of the solids.

In general, the process of the invention is conducted in such a way that the azo compound of the formula (III), preferably as the sodium or potassium salt, is initially charged, that one or more compounds of the formula (II), preferably melamine, is/are added and then reaction is effected successively or simultaneously with at least one nickel salt and at least one Me¹ salt and optionally at least one Me² salt, preferably in the form of the aqueous solutions of these salts, preferably at pH values less than 7.

Suitable substances for adjusting the pH are sodium hydroxide solution, potassium hydroxide solution, sodium carbonate, sodium hydrogencarbonate, potassium carbonate and potassium hydrogencarbonate.

Useful nickel salts preferably include the water-soluble salts thereof, especially chlorides, bromides, acetates, formates, nitrates, sulphates, etc. Nickel salts used with preference have a water solubility of more than 20 g/l, especially more than 50 g/l, at 20° C.

Useful Me¹ salts are preferably the water-soluble salts of the di- or trivalent metals lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, ytterbium, erbium, thulium, more preferably of the di- or trivalent metals lanthanum, cerium, praseodymium, neodymium, samarium, terbium and holmium, preferably the chlorides, bromides, acetates, nitrates and sulphates thereof, more preferably the chlorides thereof.

Useful Me² salts likewise preferably include the water-soluble salts of the di- and trivalent metals zinc, copper, aluminium, iron, cobalt, magnesium, calcium, strontium, manganese, yttrium, scandium, titanium, niobium, molybdenum, vanadium, zirconium, cadmium, chromium, lead and barium, preferably zinc, copper, aluminium, iron, cobalt, magnesium, calcium, strontium, manganese and yttrium and more preferably zinc, copper, aluminium, iron, cobalt and strontium, preferably the chlorides, bromides, acetates, nitrates and sulphates thereof, more preferably the chlorides thereof.

The metal azo pigments of the invention obtained in this way can then be isolated by filtration of the aqueous suspensions thereof as an aqueous filtercake. This filtercake, optionally after washing with hot water, can be dried by means of standard drying methods.

Useful drying methods include, for example, paddle drying or spray drying of corresponding aqueous slurries.

Subsequently, the pigment can be reground.

If the metal azo pigments of the invention have excessively hard grains or are too hard to be dispersed for the desired application, they can be converted to soft-grained pigments, for example by the method described in DE-A 19 847 586.

The present invention further provides a process for producing the metal azo pigments of the invention, which is characterized in that

-   -   (i) at least one adduct of         -   a1) a metal azo compound containing structural units of the             above-specified formula (I)         -   in which         -   R¹, R², R³, R⁴ and R⁵ have the above-specified general and             preferred definition,         -   and         -   Ni²⁺ ions,         -   and         -   b1) at least one compound of the above-specified             formula (II) in which R⁶ has the general and preferred             definitions given above,         -   and the amount of Ni²⁺ metal ions is 100 mol %, based on one             mole of all metal ions in the adduct a1)/b1),             with     -   (ii) at least one adduct of         -   a2) a metal azo compound containing structural units of the             above-specified formula (I)         -   in which         -   R¹, R², R³, R⁴ and R⁵ have the above-specified general and             preferred definition,             -   and         -   metal ions Me¹,         -   where         -   Me¹ is a metal ion selected from the group of         -   La³⁺, Ce³⁺, Pr³⁺, Nd²⁺, Nd³⁺, Sm²⁺, Sm³⁺, Eu²⁺, Eu³⁺, Gd³⁺,             Tb³⁺, Dy³⁺, Ho³⁺, Er³⁺, Tm³⁺, Yb²⁺ and Yb³⁺, preferably from             the group of La³⁺, Ce³⁺, Pr³⁺, Nd³⁺, Sm³⁺, Eu³⁺, Gd³⁺, Tb³⁺,             Dy³⁺, Ho³⁺, Er³⁺, Tm³⁺ and Yb³⁺, and more preferably from             the group of La³⁺, Ce³⁺, Pr³⁺, Nd³⁺, Sm³⁺, Tb³⁺ and Ho³⁺,         -   and         -   b2) at least one compound of the above-specified             formula (II) in which R⁶ has the general and preferred             definitions given above,     -   and the amount of Me¹ metal ions is 100 mol %, based on one mole         of all metal ions in the adduct a2)/b2),         and optionally with     -   (iii) at least one adduct of         -   a3) a metal azo compound containing structural units of the             above-specified formula (I)         -   in which         -   R¹, R², R³, R⁴ and R⁵ have the above-specified general and             preferred definition,         -   and         -   metal ions Me²,         -   where         -   Me² is a metal ion selected from the group of Mg²⁺, Ca²⁺,             Sr²⁺, Ba²⁺, Sc³⁺, Y³⁺, Ti²⁺, Ti³⁺, Zr²⁺, Zr³⁺, V²⁺, V³⁺,             Nb³⁺, Cr³⁺, Mo²⁺, Mo³⁺, Mn²⁺, Fe²⁺, Fe³⁺, Co²⁺, Co³⁺, Cu²⁺,             Zn²⁺, Cd²⁺, Al³⁺ and Pb²⁺, preferably from the group of             Mg²⁺, Ca²⁺, Sr²⁺, Y³⁺, Mn²⁺, Fe²⁺, Fe³⁺, Co²⁺, Co³⁺, Cu²⁺,             Zn², Al³⁺, and more preferably from the group of Sr²⁺, Fe²⁺,             Fe³⁺, Co²⁺, Co³⁺, Cu²⁺, Zn²⁺ and Al³⁺,         -   and         -   b3) at least one compound of the above-specified             formula (II) in which R⁶ has the general and preferred             definitions given above,             and the amount of Me² metal ions is 100 mol %, based on one             mole of all metal ions in the adduct a3)/b2),             are mixed with one another, where 0.05 to 1.1 mol of adduct             a2)/b2) are used and 0 to 0.05 mol of adduct a3)/b3) are             used per mole of adduct a1)/b1).

Preference is given to the preparation of binary adduct mixtures, wherein 0.25 to 0.5 mol of adduct a2)/b2) are used per mole of adduct a1)/b1), preferably 0.33 to 0.43 mol of adduct a2)/b2) per mole of adduct a1)/b1).

The metal azo pigments of the invention are notable for particularly good dispersibility and a high colour intensity. Chroma and transparency have excellent adjustability.

The metal azo pigments of the invention are of excellent suitability for all pigment applications, especially also in the form of the pigment preparations thereof.

The present invention further provides pigment preparations comprising at least one metal azo pigment of the invention and at least one auxiliary and/or additive.

Useful auxiliaries or additives generally include all additions that are customary for pigment preparations, for example those from the group of the surface-active agents such as dispersants, surfactants, wetting agents, emulsifiers, and those from the group of the surface-covering agents, bases and solvents. In principle, the auxiliary or additive is guided by the nature of the target system. If the target system is, for example, a lacquer or a printing ink, the auxiliary or additive is then selected so as to achieve maximum compatibility with the target system.

Preferably, the pigment preparations of the invention comprise at least one surface-active agent.

Surface-active agents in the context of the present invention are especially understood to mean dispersants, which stabilize the pigment particles in their fine particulate form in aqueous media. “Fine particulate” is preferably understood to mean a fine distribution of 0.001 to 5 μm, especially of 0.005 to 1 μm, more preferably of 0.005 to 0.5 μm. The pigment preparation of the invention is preferably in fine particulate form.

Suitable surface-active agents are, for example, anionic, cationic, amphoteric or nonionic in nature.

Suitable anionic surface-active agents (c) are especially condensation products of aromatic sulphonic acids with formaldehyde, such as condensation products of formaldehyde and alkylnaphthalenesulphonic acids or of formaldehyde, naphthalenesulphonic acids and/or benzenesulphonic acids, condensation products of optionally substituted phenol with formaldehyde and sodium bisulphite. Also suitable are surface-active agents from the group of the sulphosuccinic esters and alkylbenzenesulphonates. Also ionically modified, especially sulphated or carboxylated, alkoxylated fatty acid alcohols or salts thereof. Alkoxylated fatty acid alcohols are especially understood to mean those C₆-C₂₂ fatty acid alcohols endowed with 5 to 120, preferably 5 to 60 and especially with 5 to 30 mol of ethylene oxide, which are saturated or unsaturated. Additionally useful are lignosulphonates in particular, for example those which are obtained by the sulphite or Kraft process. They are preferably products which are partially hydrolysed, oxidized, propoxylated, sulphonated, sulphomethylated or desulphonated and which are fractionated by known methods, for example according to the molecular weight or the degree of sulphionation. Mixtures of sulphite and Kraft lignosulphonates are also very effective. Especially suitable are lignosulphonates with an average molecular weight between 1000 and 100 000 g/mol, a content of active lignosulphonate of at least 80% by weight and, preferably, a low content of polyvalent cations. The degree of sulphonation can be varied within wide limits.

Examples of useful nonionic surface-active agents include: reaction products of alkylene oxides with compounds capable of being alkylated, such as, for example, fatty alcohols, fatty amines, fatty acids, phenols, alkylphenols, arylalkylphenols, such as styrene-phenol condensates, carboxamides and resin acids. These are, for example, ethylene oxide adducts from the class of the reaction products of ethylene oxide with:

1) saturated and/or unsaturated fatty alcohols having 6 to 22 carbon atoms or

2) alkylphenols having 4 to 12 carbon atoms in the alkyl radical or

3) saturated and/or unsaturated fatty amines having 14 to 20 carbon atoms or

4) saturated and/or unsaturated fatty acids having 14 to 20 carbon atoms or

5) hydrogenated and/or unhydrogenated resin acids.

Useful ethylene oxide adducts especially include the alkylatable compounds mentioned in 1) to 5) having 5 to 120, especially 5 to 100, especially 5 to 60 and more preferably 5 to 30 mol of ethylene oxide.

Suitable surface-active agents are likewise the esters of the alkoxylation product of the formula (X) that are known from DE-A 19 712 486 or from DE-A 19 535 246, which correspond to the formula (XI), and the latter optionally in a mixture with the parent compounds

of the formula (X). The alkoxylation product of a styrene-phenol condensate of the formula (X) is as defined below:

in which

-   R¹⁵ is hydrogen or C₁-C₄-alkyl, -   R¹⁶ is hydrogen or CH₃, -   R¹⁷ is hydrogen, C₁-C₄-alkyl, C₁-C₄-alkoxy, C₁-C₄-alkoxycarbonyl or     phenyl, -   m is a number from 1 to 4, -   n is a number from 6 to 120, -   R¹⁸ is the same or different for every unit indicated by n and is     hydrogen, CH₃ or phenyl, where, in the case that CH₃ is present in     some of the different —(—CH₂—CH(R¹⁸)—O—) groups, R¹⁸ is CH₂ in 0% to     60% of the total value of n and R¹⁸ is hydrogen in 100% to 40% of     the total value of n, and where, in the case that phenyl is present     in some of the different —(—CH₂—CH(R¹⁸)—O—) groups, R¹⁸ is phenyl in     0% to 40% of the total value of n and R¹⁸ is hydrogen in 100% to 60%     of the total value of n.

The esters of the alkoxylation products (X) correspond to the formula (XI)

in which

-   R^(15′), R^(16′), R^(17′), R^(18′), m′ and n′ assume the scope of     the definition of R¹⁵, R¹⁶, R¹⁷, R¹⁸, m and n, but independently     thereof, -   X is the —SO₃, SO₂, —PO₃ or —CO—(R¹⁹)—COO group, -   Kat is a cation from the group of H, Li, Na, K, NH₄ or     HO—CH₂CH₂—NH₃, where two Kat are present in that case that X=—PO₃,     and -   R¹⁹ is a divalent aliphatic or aromatic radical, preferably     C₁-C₄-alkylene, especially ethylene, C₂-C₄ monounsaturated radicals,     especially acetylene or optionally substituted phenylene, especially     ortho-phenylene, where possible substituents preferably include     C₁-C₄-alkyl, C₁-C₄-alkoxy, C₁-C₄-alkoxycarbonyl or phenyl.

A preferred surface-active agent used is the compound of the formula (XI). Preferably a compound of the formula (XI) in which X is a radical of the formula —CO—(R¹⁹)—COO⁻ and R¹⁹ is as defined above.

Preference is likewise given to using, as surface-active agent, a compound of the formula (XI) together with a compound of the formula (X). Preferably, the surface-active agent in this case contains 5% to 99% by weight of the compound (XI) and 1% to 95% by weight of the compound (X).

The surface-active agent of component (c) is preferably used in the pigment preparation in an amount of 0.1% to 100% by weight, especially 0.5% to 80% by weight, based on the metal azo pigment of the invention used.

It will be appreciated that the pigment preparation of the invention may also contain further additions. For example, additions which lower the viscosity of an aqueous suspension and/or increase the solids content, for example carboxamides and sulphonamides, may be added in an amount of up to 10% by weight, based on the pigment preparation.

Further additions are, for example, inorganic and organic bases, and additions customary for pigment preparations.

Bases include: alkali metal hydroxides, for example NaOH, KOH or organic amines such as alkylamines, especially alkanolamines or alkylalkanolamines.

Particularly preferred examples include methylamine, dimethylamine, trimethylamine, ethanolamine, n-propanolamine, n-butanolamine, diethanolamine, triethanolamine, methylethanolamine or dimethylethanolamine.

Examples of suitable carboxamides and sulphonamides include: urea and substituted ureas such as phenylurea, dodecylurea and others; heterocycles such as barbituric acid, banzimidazolone, benzimidazolone-5-sulphonic acid, 2,3-dihydroxyquinoxaline, 2,3-dihydroxyquinoxaline-6-sulphonic acid, carbazole, carbazole-3,6-disulphonic acid, 2-hydroxyquinoline, 2,4-dihydroxyquinoline, caprolactam, melamine, 6-phenyl-1,3,5-triazine-2,4-diamine, 6-methyl-1,3,5-triazine-2,4-diamine, cyanuric acid.

The base is optionally present up to an amount of 20% by weight, preferably to 10% by weight, based on the pigment.

In addition, the pigment preparations of the invention may still contain inorganic and/or organic salts as a result of the preparation.

The pigment preparations of the invention are preferably solid at room temperature. More particularly, the pigment preparations of the invention are in the form of powders or granules.

The pigment preparations of the invention are of excellent suitability for all pigment applications.

The present invention further provides for the use of at least one metal azo pigment of the invention or of a pigment preparation of the invention for pigmentation of all kinds of lacquers for the production of printing inks, distempers or emulsion paints, for the bulk colouring of paper, for the bulk colouring of synthetic, semisynthetic or natural macromolecular substances, for example polyvinyl chloride, polystyrene, polyamide, polyethylene or polypropylene. They can also be used for the spin dyeing of natural, regenerated or synthetic fibres, for example cellulose, polyester, polycarbonate, polyacrylonitrile or polyamide fibres, and for printing of textiles and paper. These pigments can be used to produce finely divided, stable, aqueous pigmentations for emulsion paints and other paints usable for paper colouring, for the pigment printing of textiles, for laminate printing or for the spin dyeing of viscose, by grinding or kneading in the presence of nonionic, anionic or cationic surfactants.

The metal azo pigments of the invention are additionally of excellent suitability for inkjet applications and for colour filters for liquid-crystal displays.

In a likewise preferred embodiment, the pigment preparations of the invention comprise at least one organic compound (d) selected from the group of the terpenes, terpenoids, fatty acids, fatty acid esters and the homo- or copolymers, such as random or block copolymers having a solubility in pH-neutral water at 20° C. of less than 1 g/l, especially less than 0.1 g/l. The organic compound (d) is preferably solid or liquid at room temperature (20° C.) under standard atmosphere and, if it is liquid, has a boiling point of preferably >100° C., especially >150° C.

Preferred polymers have both a hydrophilic and a hydrophobic, preferably polymeric, molecular moiety. Examples of such polymers are random copolymers based on fatty acids or long-chain C₁₂-C₂₂ hydrocarbons and polyalkylene glycols, especially polyethylene glycol. Also block copolymers based on (poly)hydroxy fatty acids and polyalkylene glycol, especially polyethylene glycol, and also graft copolymers based on poly(meth)acrylate and polyalkylene glycol, especially polyethylene glycol.

Preferred compounds from the group of the terpenes, terpenoids, fatty acids and fatty acid esters include: ocimene, myrcene, geraniol, nerd, linalool, citronellol, geranial, citronellal, neral, limonene, menthol, for example (−)-menthol, menthone or bicyclic monoterpenes, saturated and unsaturated fatty acids having 6 to 22 carbon atoms, for example oleic acid, linoleic acid and linolenic acid or mixtures thereof.

Also useful as organic compounds of component (d) are the abovementioned adduct formers, provided that they obey the criteria desired for the compound of component (d).

Particularly preferred pigment preparations comprise:

50%-99% by weight of at least one metal azo pigment of the invention and

1%-50% by weight, preferably 2% to 50% by weight of at least one compound of component (d).

Optionally, the pigment preparation of the invention additionally comprises a surface-active agent (c).

More preferably, the preparations of the invention consist to an extent of more than 90% by weight, preferably more than 95% by weight and especially more than 87% by weight of at least one metal azo pigment of the invention, at least one organic compound of component (d) and optionally at least one surface-active agent of component (c) and optionally at least one base.

The pigment preparations of the invention in this composition are especially suitable for pigmentation of inkjet inks and colour filters for liquid-crystal displays.

The present invention further provides a process for producing the pigment preparations of the invention, which is characterized in that at least one metal azo pigment of the invention and at least one auxiliary or additive, especially at least one organic compound of component (d) and optionally at least one surface-active agent of component (c) and optionally at least one base are mixed with one another.

The present invention likewise provides for the use of the metal azo pigments of the invention or of the pigment preparations of the invention for production of colour filters for liquid-crystal displays. This use will be described hereinafter using the example of the pigment dispersion method according to the photoresist process.

The inventive use of the pigment preparations of the invention for production of colour filters is characterized in that, for example, at least one metal azo pigment of the invention or a pigment preparation of the invention, especially a solid pigment preparation, is homogenized, optionally with a binder resin and an organic solvent, optionally with addition of a dispersant, and then wet-comminuted continuously or batchwise to a particle size by number (electron microscopy determination) of 99.5%<1000 nm, preferably 95%<500 nm and especially 90%<200 nm.

Useful wet comminution methods include, for example, stirrer or dissolver dispersion, grinding by means of stirred ball mills or bead mills, kneaders, roll mills, high-pressure homogenization or ultrasound dispersion.

During the dispersion treatment or thereafter, at least one photocurable monomer and a photoinitiator are added. After the dispersion, it is possible to introduce further binder resin, solvent, or admixtures customary for photoresists, as required for the desired photosensitive coating formulation (photoresist) for production of the colour filters. In the context of this invention, a photoresist is understood to mean a preparation comprising at least one photocurable monomer and a photoinitiator.

The present invention also provides a process for producing colour filters for liquid-crystal displays, which is characterized in that at least one metal azo pigment of the invention or a pigment preparation of the invention is homogenized, optionally with a binder resin and an organic solvent, optionally with addition of a dispersant, and then wet-comminuted continuously or batch wise to a particle size by number (electron microscopy determination) of 99.5%<1000 nm and, during the dispersion treatment or thereafter, at least one photocurable monomer and a photoinitiator are added.

Useful possible dispersants include dispersants which are suitable for this application and are generally commercially available, for example polymeric, ionic or nonionic dispersants, for example based on polycarboxylic acids or polysulphonic acids, and also polyethylene oxide-polypropylene oxide block copolymers. In addition, it is also possible to use derivatives of organic dyes as dispersants or co-dispersants.

The production of colour filters therefore gives rise to “formulations” comprising, based on the formulation:

-   -   at least one metal azo pigment of the invention,         -   optionally a binder resin,         -   at least one organic solvent and         -   optionally a dispersant.

In a preferred embodiment, the formulation contains (figures based on formulation);

1%-50% by weight of a metal azo pigment of the invention

0%-20% by weight of binder resin

0%-20% by weight of dispersant

10%-94% by weight of organic solvent.

The coating of the photoresist onto a plate to produce the coloured image element patterns can be accomplished either by direct or indirect application. Examples of application methods include: roller coating, spin coating, spray coating, dip coating and air-knife coating.

Useful plates include, according to the application, for example: transparent glasses such as white or blue glass plates, silicate-coated blue glass plate, synthetic resin plate or films based, for example, on polyester resin, polycarbonate resin, acrylic resin or vinyl chloride resin, and also metal plates based on aluminium, copper, nickel or steel, and ceramic plates or semiconductor plates having applied photoelectric transfer elements.

The application is generally effected such that the layer thickness of the photosensitive layer obtained is 0.1 to 10 μm.

The application may be followed by thermal drying of the layer.

The exposure is preferably effected by exposing the photosensitive layer to an active light beam, preferably in the form of an image pattern by means of a photomask. In this way, the layer is cured at the exposed sites. Suitable light sources are, for example: high-pressure and ultrahigh-pressure mercury vapour lamp, xenon lamp, metal halide lamp, fluorescent lamp, and laser beam in the visible region.

The development which follows the exposure removes the unexposed portion of the coating and gives the desired image pattern form of the colour elements. Standard development methods include spraying with or dipping into aqueous alkaline developer solution or into an organic solvent comprising inorganic alkali, for example sodium hydroxide or potassium hydroxide, sodium metasilicate or organic bases such as monoethanolamine, diethanolamine, triethanolamine, triethylamine or salts thereof.

The development is generally followed by a thermal post-drying/curing of the image patterns.

The inventive use of the metal azo pigments is preferably characterized in that they are used alone or in a mixture with other pigments that are customary for the production of colour filters in the colour filters or pigment preparations or formulations for colour filters.

These “other pigments” may either be other metal salts of an azo compound of the formula (I) or pigment preparations based thereon or other inorganic or organic pigments.

With regard to the selection of any other pigments to be used as well, there is no restriction in accordance with the invention. Both inorganic and organic pigments are useful.

Preferred organic pigments are, for example, those of the monoazo, disazo, laked azo, β-naphthol, naphthol AS, benzimidazdone, disazo condensations, azo metal complex, isoindoline and isoindolinone series, and also polycyclic pigments, for example from the phthalocyanine, quinacridone, perylene, perinone, thioindigo, anthraquinone, dioxazine, quinophthalone and diketopyrrolopyrrole series. Also laked dyes such as Ca, Mg and Al lakes of sulpho- or carboxyl-containing dyes.

Examples of other organic pigments which can optionally be used in addition are:

Colour Index Pigment Yellow 12, 13, 14, 17, 20, 24, 74, 83, 86, 93, 94, 109, 110, 117, 125, 137, 138, 139, 147, 148, 150, 153, 154, 166, 173, 185, or

Colour Index Pigment Orange 13, 31, 36, 38, 40, 42, 43, 51, 55, 59, 61, 64, 65, 71, 72, 73 or

Colour Index Pigment Red 9, 97, 122, 123, 144, 149, 166, 168, 177, 180, 192, 215, 216, 224, 254, 272, or

Colour Index Pigment Green 7, 10, 36, 37, 45, 58 or

Colour Index Pigment Blue 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16 and

Colour Index Pigment Violet 19, 23.

In addition, it is also possible to use soluble organic dyes in conjunction with the novel pigments of the invention.

If “other pigments” are used in addition, the proportion of metal azo pigment of the invention is preferably 1%-99% by weight, especially 20%-80% by weight, based on the total amount of all pigments used. Particular preference is given to the pigment preparations of the invention and to formulations comprising at least one metal azo pigment of the invention and C.I. Pigment Green 36 and/or C.I. Pigment Green 58 in a ratio of 20% to 80% by weight of metal azo pigment to 80% to 20% by weight of C.I. Pigment Green 36 and/or C.I. Pigment Green 58, preferably of 40% to 60% by weight to 60% to 40% by weight.

There is no particular restriction in accordance with the invention with regard to the binder resins which can be used together with the “pigment” or pigment preparations based thereon in colour filters or in the formulations for production of colour filters, for example by the pigment dispersion method, and useful binder resins are especially the film-forming resins known per se for use in colour filters.

For example, useful binder resins include those from the group of the cellulose resins such as carboxymethyl hydroxyethyl cellulose and hydroxyethyl cellulose, acrylic resins, alkyd resins, melamine resins, epoxy resins, polyvinyl alcohols, polyvinylpyrrolidones, polyamides, polyamide imines, polyimides,

polyimide precursors such as those of the formula (14), disclosed in JP-A 11 217 514, and the esterification products thereof.

Examples of these include reaction products of tetracarboxylic dianhydride with diamines.

Useful binder resins also include those which contain photopolymerizable unsaturated bonds. The binder resins may, for example, be those formed from the group of acrylic resins. Particular mention should be made here of homo- and copolymers of polymerizable monomers, for example methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, styrene and styrene derivatives, and also copolymers between carboxyl-bearing polymerizable monomers such as (meth)acrylic acid, itaconic acid, maleic acid, maleic anhydride, monoalkyl maleates, especially with alkyl having 1 to 12 carbon atoms, and polymerizable monomers such as (meth)acrylic acid, styrene and styrene derivatives, for example α-methylstyrene, m- or p-methoxystyrene, p-hydroxystyrene. Examples include reaction products of carboxyl-containing polymeric compounds with compounds each containing an oxirane ring and an ethylenically unsaturated bond, for example glycidyl (meth)acrylate, acryloyl glycidyl ether and itaconic acid monoalkyl glycidyl ether, etc., and also reaction products of carboxyl-containing polymeric compounds with compounds each containing a hydroxyl group and an ethylenically unsaturated bond (unsaturated alcohols), such as allyl alcohol, 2-buten-4-ol, oleyl alcohol, 2-hydroxyethyl (meth)acrylate, N-methylolacrylamide, etc.;

In addition, such binder resins may also contain unsaturated compounds having free isocyanate groups.

In general, the equivalents of unsaturation (molar mass of binder resin per unsaturated compound) of the binder resins mentioned are 200 to 3000, especially 230 to 1000, in order to achieve both sufficient photopolymerizability and hardness of the film. The acid value is generally 20 to 300, especially 40 to 200, in order to achieve sufficient alkali development capacity after the exposure of the film.

The mean molar mass of the binder resins for use is between 1500 and 200 000 and is especially 10 000 to 50 000 g/mol.

The organic solvents used in the inventive use of the pigment preparations for colour filters are, for example, ketones, alkylene glycol ethers, alcohols and aromatic compounds. Examples from the group of the ketones are: acetone, methyl ethyl ketone, cyclohexanone, etc.; from the group of the alkylene glycol ethers: Methyl Cellosolve (ethylene glycol monomethyl ester), Butyl Cellosolve (ethylene glycol monobutyl ether) Methyl Cellosolve Acetate, Ethyl Cellosolve Acetate, Butyl Cellosolve Acetate, ethylene glycol monopropyl ether, ethylene glycol monohexyl ether, ethylene glycol dimethyl ether, diethylene glycol ethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol monomethyl ether acetate, diethylene glycol methyl ether acetate, diethylene glycol ethyl ether acetate, diethylene glycol propyl ether acetate, diethylene glycol isopropyl ether acetate, diethylene glycol butyl ether acetate, diethylene glycol t-butyl ether acetate, triethylene glycol methyl ether acetate, triethylene glycol ethyl ether acetate, triethylene glycol propyl ether acetate, triethylene glycol isopropyl ether acetate, triethylene glycol butyl ether acetate, triethylene glycol t-butyl ether acetate, etc.; from the group of the alcohols: methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butyl alcohol, 3-methyl-3-methoxybutanol, etc.; from the group of the aromatic solvents: benzene, toluene, xylene, N-methyl-2-pyrrolidone, ethyl N-hydroxymethyl-2-acetate, etc.

Further other solvents are propane-1,2-diol diacetate, 3-methyl-3-methoxybutyl acetate, ethyl acetate, tetrahydrofuran, etc. The solvents may be used individually or in mixtures with one another.

The invention further relates to a photoresist comprising at least one metal azo pigment of the invention or at least one pigment preparation of the invention and at least one photocurable monomer and at least one photoinitiator.

The photocurable monomers contain at least one reactive double bond and optionally other reactive groups in the molecule.

Photocurable monomers are understood in this connection especially to mean reactive solvents or what are called reactive diluents, for example from the group of the mono-, di-, tri- and multifunctional acrylates and methacrylates, vinyl ethers and glycidyl ethers. Useful reactive groups additionally present include allyl, hydroxyl, phosphate, urethane, secondary amine and N-alkoxymethyl groups.

Monomers of this kind are known to those skilled in the art and are detailed, for example, in [Römpp Lexikon, Lacke und Druckfarben, Dr. Ulrich Zorll, Thieme Verlag Stuttgart-New York, 1996, p. 491/492].

The selection of monomers is guided especially by the nature and intensity of the radiation type used for the exposure, the desired reaction with the photoinitiator and the film properties. It is also possible to use combinations of monomers.

Reaction photoinitiators or photoinitiators are understood to mean compounds which form reactive intermediates as a result of the absorption of visible or ultraviolet radiation, which can trigger a polymerization reaction, for example of the abovementioned monomers and/or binder resins. Reaction photoinitiators are likewise commonly known and can likewise be found in [Römpp Lexikon, Lacke und Druckfarben, Dr. Ulrich Zorll, Thieme Verlag Stuttgart-New York, 1998, p. 445/446].

According to the invention, there is no restriction with regard to the photocurable monomers or photoinitiators to be used.

The invention preferably relates to photoresists comprising

-   A) at least one metal azo pigment of the invention, especially in a     mixture with other pigments, preferably C.I. Pigment Green 36 and/or     Pigment Green 58 or a pigment preparation of the invention based     thereon, -   B1) at least one photocurable monomer, -   B2) at least one photoinitiator, -   C1) optionally an organic solvent, -   D) optionally a dispersant, -   E) optionally a binder resin,     and optionally further additions.

According to the invention, there is also no restriction with regard to the methodology for production of the coloured image element patterns based on the pigments or solid pigment preparations for use in accordance with the invention. As well as the above-described photolithographic method, other methods such as offset printing, chemical etching or inkjet printing are likewise suitable. The selection of the suitable binder resins and solvents and of pigment carrier media and further additions should be matched to the particular method. In the inkjet method, which is understood to mean both thermal and mechanical and piezo-mechanical inkjet printing, useful carrier media for the pigments and any binder resins are not only purely organic but also aqueous-organic carrier media; aqueous-organic carrier media are actually preferred.

The examples which follow are intended to illustrate the present invention but without restricting it thereto.

EXAMPLES

Preparation of the Azobarbituric Acid Precursor (Method 1)

46.2 g of diazobarbituric acid and 38.4 g of barbituric acid are introduced into 1100 g of distilled water at 85° C. Subsequently, aqueous potassium hydroxide solution was used to establish a pH of about 5 and the mixture was stirred for 90 min.

Example 1

1500 g of distilled water were added at 82° C. to an azobarbituric acid prepared according to Method 1. Subsequently, 10 g of 30% hydrochloric acid were added dropwise. Thereafter, 79.4 g of melamine were introduced. Subsequently, 0.3 mol of an about 25% nickel chloride solution was added dropwise. After 3 h at 82° C., KOH was used to establish a pH of about 5.5. Thereafter, dilution was effected at 90° C. with about 100 g of distilled water. Subsequently, 21 g of 30% hydrochloric acid were added dropwise and the mixture was heat-treated at 90° C. for 12 h. Thereafter, aqueous potassium hydroxide solution was used for adjustment to a pH of about 5. Subsequently, the pigment was isolated on a suction filter, washed and dried in a vacuum drying cabinet at 80° C., and ground in a standard laboratory mill for about 2 minutes. (=pigment 1, not inventive).

Examples 2 to 71

For production of the inventive pigments 2 to 47 and of the noninventive pigments 49 to 71, the procedure in each case was analogous to Example 1. In each case, 5000 g of distilled water were added to an azobarbituric acid prepared according to Method 1 at 82° C., and then 252.2 g of melamine were introduced. Subsequently, rather than the nickel chloride solution of example 1, a metal salt solution as specified in the examples which follow was added dropwise in each case. The workup and isolation, drying and grinding of the respective pigment in all examples was effected analogously to the method specified in Example 1.

Example 2

A mixture of 0.285 mol of an about 25% nickel chloride solution and 0.010 mol of an about 10% gadolinium(III) chloride solution was added dropwise.

Example 3

A mixture of 0.240 mol of an about 25% nickel chloride solution and 0.040 mol of an about 10% gadolinium(III) chloride solution was added dropwise.

Example 4

A mixture of 0.285 mol of an about 25% nickel chloride solution and 0.010 mol of an about 10% holmium(III) chloride solution was added dropwise.

Example 5

A mixture of 0.240 mol of an about 25% nickel chloride solution and 0.040 mol of an about 10% holmium(III) chloride solution was added dropwise.

Example 6

A mixture of 0.285 mol of an about 25% nickel chloride solution and 0.010 mol of an about 10% samarium(III) chloride solution was added dropwise.

Example 7

A mixture of 0.240 mol of an about 25% nickel chloride solution and 0.040 mol of an about 10% samarium(III) chloride solution was added dropwise.

Example 8

A mixture of 0.285 mol of an about 25% nickel chloride solution and 0.010 mol of an about 10% terbium(III) chloride solution was added dropwise.

Example 9

A mixture of 0.240 mol of an about 25% nickel chloride solution and 0.040 mol of an about 10% terbium(III) chloride solution was added dropwise.

Example 10

A mixture of 0.285 mol of an about 25% nickel chloride solution and 0.010 mol of an about 10% ytterbium(III) chloride solution was added dropwise.

Example 11

A mixture of 0.240 mol of an about 25% nickel chloride solution and 0.040 mol of an about 10% ytterbium(III) chloride solution was added dropwise.

Example 12

A mixture of 0.285 mol of an about 25% nickel chloride solution and 0.010 mol of an about 10% erbium(III) chloride solution was added dropwise.

Example 13

A mixture of 0.240 mol of an about 25% nickel chloride solution and 0.040 mol of an about 10% erbium(III) chloride solution was added drop wise.

Example 14

A mixture of 0.285 mol of an about 25% nickel chloride solution and 0.010 mol of an about 10% dysprosium(III) chloride solution was added dropwise.

Example 15

A mixture of 0.240 mol of an about 25% nickel chloride solution and 0.040 mol of an about 10% dysprosium(III) chloride solution was added drop wise.

Example 18

A mixture of 0.285 mol of an about 25% nickel chloride solution and 0.010 mol of an about 10% neodymium(III) chloride solution was added dropwise.

Example 17

A mixture of 0.240 mol of an about 25% nickel chloride solution and 0.040 mol of an about 10% neodymium(III) chloride solution was added drop wise.

Example 18

A mixture of 0.285 mol of an about 25% nickel chloride solution and 0.010 mol of an about 10% europium(III) chloride solution was added drop wise.

Example 19

A mixture of 0.240 mol of an about 25% nickel chloride solution and 0.040 mol of an about 10% europium(III) chloride solution was added dropwise.

Example 20

A mixture of 0.285 mol of an about 25% nickel chloride solution and 0.010 mol of an about 10% praseodymium(III) chloride solution was added dropwise.

Example 21

A mixture of 0.240 mol of an about 25% nickel chloride solution and 0.040 mol of an about 10% praseodymium(III) chloride solution was added dropwise.

Example 22

A mixture of 0.285 mol of an about 25% nickel chloride solution end 0.010 mol of an about 10% lanthanum(III) chloride solution was added dropwise.

Example 23

A mixture of 0.240 mol of an about 25% nickel chloride solution and 0.040 mol of an about 10% lanthanum(III) chloride solution was added dropwise.

Example 24

A mixture of 0.285 mol of an about 25% nickel chloride solution and 0.010 mol of an about 10% cerium(III) chloride solution was added dropwise.

Example 25

A mixture of 0.240 mol of an about 25% nickel chloride solution and 0.040 mol of an about 10% cerium(III) chloride solution was added dropwise.

Example 26

A mixture of 0.180 mol of an about 25% nickel chloride solution and 0.080 mol of an about 10% gadolinium(III) chloride solution was added drop wise.

Example 27

A mixture of 0.180 mol of an about 25% nickel chloride solution and 0.080 mol of an about 10% holmium(III) chloride solution was added dropwise.

Example 28

A mixture of 0.180 mol of an about 25% nickel chloride solution and 0.080 mol of an about 10% samarium(III) chloride solution was added dropwise.

Example 29

A mixture of 0.180 mol of an about 25% nickel chloride solution and 0.080 mol of an about 10% terbium(III) chloride solution was added dropwise.

Example 30

A mixture of 0.180 mol of an about 25% nickel chloride solution and 0.080 mol of an about 10% ytterbium(III) chloride solution was added dropwise.

Example 31

A mixture of 0.180 mol of an about 25% nickel chloride solution and 0.080 mol of an about 10% erbium(III) chloride solution was added dropwise.

Example 32

A mixture of 0.180 mol of an about 25% nickel chloride solution and 0.080 mol of an about 10% dysprosium(III) chloride solution was added dropwise.

Example 33

A mixture of 0.180 mol of an about 25% nickel chloride solution and 0.080 mol of an about 10% neodymium(III) chloride solution was added dropwise.

Example 34

A mixture of 0.180 mol of an about 25% nickel chloride solution and 0.080 mol of an about 10% europium(III) chloride solution was added dropwise.

Example 35

A mixture of 0.180 mol of an about 25% nickel chloride solution and 0.080 mol of an about 10% praseodymium(III) chloride solution was added dropwise.

Example 36

A mixture of 0.180 mol of an about 25% nickel chloride solution and 0.080 mol of an about 10% lanthanum(III) chloride solution was added dropwise.

Example 37

A mixture of 0.180 mol of an about 25% nickel chloride solution and 0.080 mol of an about 10% cerium(III) chloride solution was added drop wise.

Example 38

A mixture of 0.285 mol of an about 25% nickel chloride solution, 0.005 mol of an about 10% gadolinium(III) chloride solution and 0.005 mol of an about 10% holmium(III) chloride solution was added dropwise.

Example 39

A mixture of 0.264 mol of an about 25% nickel chloride solution, 0.008 mol of an about 10% gadolinium(III) chloride solution, 0.008 mol of an about 10% samarium(III) chloride solution and 0.008 mol of an about 10% holmium(III) chloride solution was added drop wise.

Example 40

A mixture of 0.282 mol of an about 25% nickel chloride solution, 0.004 mol of an about 10% dysprosium(III) chloride solution, 0.004 mol of an about 10% samarium(III) chloride solution and 0.004 mol of an about 10% holmium(III) chloride solution was added dropwise.

Example 41

A mixture of 0.240 mol of an about 25% nickel chloride solution, 0.020 mol of an about 10% terbium(III) chloride solution and 0.020 mol of an about 10% ytterbium(III) chloride solution was added drop wise.

Example 42

A mixture of 0.255 mol of an about 25% nickel chloride solution, 0.010 mol of an about 10% erbium(III) chloride solution, 0.010 mol of an about 10% dysprosium(III) chloride solution and 0.010 mol of an about 10% neodymium(III) chloride solution was added dropwise.

Example 43

A mixture of 0.285 mol of an about 25% nickel chloride solution, 0.005 mol of an about 10% gadolinium(III) chloride solution and 0.005 mol of an about 10% holmium(III) chloride solution was added dropwise.

Example 44

A mixture of 0.240 mol of an about 25% nickel chloride solution, 0.020 mol of an about 10% praseodymium(III) chloride solution and 0.020 mol of an about 10% lanthanum(III) chloride solution was added dropwise.

Example 45

A mixture of 0.282 mol of an about 25% nickel chloride solution, 0.004 mol of an about 10% lanthanum(III) chloride solution, 0.004 mol of an about 10% cerium(III) chloride solution and 0.004 mol of an about 10% ytterbium(III) chloride solution was added dropwise.

Example 46

A mixture of 0.240 mol of an about 25% nickel chloride solution, 0.01 mol of an about 10% lanthanum(III) chloride solution, 0.01 mol of an about 10% dysprosium(III) chloride solution, 0.01 mol of an about 10% praseodymium(III) chloride solution and 0.01 mol of an about 10% holmium(III) chloride solution was added dropwise.

Example 47

A mixture of 0.282 mol of an about 25% nickel chloride solution, 0.003 mol of an about 10% samarium(III) chloride solution, 0.003 mol of an about 10% holmium(III) chloride solution, 0.003 mol of an about 10% europium(III) chloride solution and 0.003 mol of an about 10% praseodymium(III) chloride solution was added dropwise.

Example 48

A mixture of 0.120 mol of an about 25% nickel chloride solution and 0.120 mol of an about 10% gadolinium(III) chloride solution was added dropwise.

Example 49

A mixture of 0.120 mol of an about 25% nickel chloride solution and 0.120 mol of an about 10% holmium(III) chloride solution was added dropwise.

Example 50

A mixture of 0.120 mol of an about 25% nickel chloride solution and 0.120 mol of an about 10% samarium(III) chloride solution was added dropwise.

Example 51

A mixture of 0.120 mol of an about 25% nickel chloride solution and 0.120 mol of an about 10% terbium(III) chloride solution was added dropwise.

Example 52

A mixture of 0.120 mol of an about 25% nickel chloride solution and 0.120 mol of an about 10% ytterbium(III) chloride solution was added dropwise.

Example 53

A mixture of 0.120 mol of an about 25% nickel chloride solution and 0.120 mol of an about 10% erbium(III) chloride solution was added dropwise.

Example 54

A mixture of 0.120 mol of an about 25% nickel chloride solution and 0.120 mol of an about 10% dysprosium(III) chloride solution was added dropwise.

Example 55

A mixture of 0.120 mol of an about 25% nickel chloride solution and 0.120 mol of an about 10% neodymium(III) chloride solution was added dropwise.

Example 56

A mixture of 0.120 mol of an about 25% nickel chloride solution and 0.120 mol of an about 10% europium(III) chloride solution was added dropwise.

Example 57

A mixture of 0.120 mol of an about 25% nickel chloride solution and 0.120 mol of an about 10% praseodymium(III) chloride solution was added dropwise.

Example 58

A mixture of 0.120 mol of en about 25% nickel chloride solution and 0.120 mol of an about 10% lanthanum(III) chloride solution was added dropwise.

Example 59

A mixture of 0.120 mol of an about 25% nickel chloride solution and 0.120 mol of an about 10% cerium(III) chloride solution was added dropwise.

Example 60

A mixture of 0.291 mol of an about 25% nickel chloride solution and 0.006 mol of an about 10% gadolinium(III) chloride solution was added dropwise.

Example 61

A mixture of 0.291 mol of an about 25% nickel chloride solution and 0.006 mol of an about 10% holmium(III) chloride solution was added dropwise.

Example 62

A mixture of 0.291 mol of an about 25% nickel chloride solution and 0.006 mol of an about 10% samarium(III) chloride solution was added dropwise.

Example 63

A mixture of 0.291 mol of an about 25% nickel chloride solution and 0.006 mol of an about 10% terbium(III) chloride solution was added dropwise.

Example 64

A mixture of 0.291 mol of an about 25% nickel chloride solution and 0.006 mol of an about 10% ytterbium(III) chloride solution was added dropwise.

Example 65

A mixture of 0.291 mol of an about 25% nickel chloride solution and 0.006 mol of an about 10% erbium(III) chloride solution was added dropwise.

Example 66

A mixture of 0.297 mol of an about 25% nickel chloride solution and 0.002 mol of an about 10% dysprosium(III) chloride solution was added dropwise.

Example 67

A mixture of 0.297 mol of an about 25% nickel chloride solution and 0.002 mol of an about 10% neodymium(III) chloride solution was added dropwise.

Example 66

A mixture of 0.297 mol of an about 25% nickel chloride solution and 0.002 mol of an about 10% europium(III) chloride solution was added dropwise.

Example 69

A mixture of 0.297 mol of an about 25% nickel chloride solution and 0.002 mol of an about 10% praseodymium(III) chloride solution was added dropwise.

Example 70

A mixture of 0.297 mol of an about 25% nickel chloride solution and 0.002 mol of an about 10% lanthanum(III) chloride solution was added dropwise.

Example 71

A mixture of 0.297 mol of an about 25% nickel chloride solution and 0.002 mol of an about 10% cerium(III) chloride solution was added dropwise.

Determination of Colour Strength in PVC

Pigments 1 to 71 prepared according to Examples 1 to 71 were each subjected to a determination of colour strength by the method which follows. The results are listed in Table 1.

The test medium produced was a flexible PVC compound, by homogenizing 67.5% Vestolit® E7004 (Vestolit GmbH), 29.0% Hexamoll® Dinch (BASF), 2.25% Baerostab UBZ 770 (Baerlocher GmbH) and 1.25% Isocolor white pigment paste (ISL-Chemie) with a laboratory dissolver.

A laboratory roll mill was used to add 100 g of the PVC compound at 150° C. to two rollers of diameter 150 mm that rotate at 20 min⁻¹ and 18 min⁻¹. Together with 0.10 g of pigment, the milled sheet that formed was guided through a roller gap of 0.10 mm eight times. Then the homogeneously coloured milled sheet was removed with a roller gap of 0.8 mm and laid out flat over a metal surface. The cooled milled sheet was then passed through a roller gap of 0.2 mm between two heated rollers of diameter 110 mm that rotate at 26 min⁻¹ and 24 min⁻¹ eight times. To smooth the surface, this milled sheet was applied to the rollers at 150° C. once again, removed at 0.8 mm and left to cool on a smooth surface. Specimens of this sheet served to determine the relative colour strength.

The relative colour strength was calculated after measuring the reflectance of the specimens against a white background by means of a spectrophotometer with d/8 measurement geometry under D65 illuminant with a 10° observer according to DIN 55986 using the sum total of the K/S values over the visible spectrum (400 nm-700 mm).

TABLE 1 Colour strength Sample Use val % Status % Pigment 1  100% Ni noninventive 100 Pigment 2   5% Gd inventive 107 Pigment 3   20% Gd inventive 115 Pigment 4   5% Ho inventive 108 Pigment 5   20% Ho inventive 116 Pigment 6   5% Sm inventive 105 Pigment 7   20% Sm inventive 113 Pigment 8   5% Tb inventive 106 Pigment 9   20% Tb inventive 115 Pigment 10   5% Yb inventive 105 Pigment 11   20% Yb inventive 116 Pigment 12   5% Er inventive 107 Pigment 13   20% Er inventive 117 Pigment 14   5% Dy inventive 106 Pigment 15   20% Dy inventive 116 Pigment 16   5% Nd inventive 107 Pigment 17   20% Nd inventive 118 Pigment 18   5% Eu inventive 106 Pigment 19   20% Eu inventive 117 Pigment 20   5% Pr inventive 108 Pigment 21   20% Pr inventive 118 Pigment 22   5% La inventive 105 Pigment 23   20% La inventive 116 Pigment 24   5% Ce inventive 106 Pigment 25   20% Ce inventive 117 Pigment 26   30% Gd inventive 120 Pigment 27   40% Ho inventive 121 Pigment 28   40% Sm inventive 123 Pigment 29   40% Tb inventive 121 Pigment 30   40% Yb inventive 122 Pigment 31   40% Er inventive 124 Pigment 32   40% Dy inventive 123 Pigment 33   40% Nd inventive 124 Pigment 34   40% Eu inventive 124 Pigment 35   40% Pr inventive 125 Pigment 36   40% La inventive 123 Pigment 37   40% Ce inventive 124 Pigment 38  2.5% Gd, 2.5% Ho inventive 107 Pigment 39   4% Gd, 4% Ho, 4% Sm inventive 112 Pigment 40   2% Dy, 2% Ho, 2% Sm inventive 108 Pigment 41   10% Tb, 10% Yb inventive 118 Pigment 42   5% Er, 5% Dy, 5% Nd inventive 113 Pigment 43  2.5% Pr, 2.5% Eu inventive 109 Pigment 44   10% Pr, 10% La inventive 116 Pigment 45   2% La, 2% Ce, 2% Yb inventive 110 Pigment 46   5% La, 5% Dy, 5% Pr, 5% Ho inventive 116 Pigment 47  1.5% Sm, 1.5% Ho, 1.5% Eu, inventive 108  1.5% Pr Pigment 48   60% Gd noninventive 98 Pigment 49   60% Ho noninventive 99 Pigment 50   60% Sm noninventive 97 Pigment 51   60% Tb noninventive 96 Pigment 52   60% Yb noninventive 98 Pigment 53   60% Er noninventive 99 Pigment 54   60% Dy noninventive 96 Pigment 55   60% Nd noninventive 98 Pigment 56   60% Eu noninventive 99 Pigment 57   60% Pr noninventive 97 Pigment 58   60% La noninventive 96 Pigment 59   60% Ce noninventive 98 Pigment 60   3% Gd noninventive 98 Pigment 61   3% Ho noninventive 99 Pigment 62   3% Sm noninventive 96 Pigment 63   3% Tb noninventive 97 Pigment 64   3% Yb noninventive 96 Pigment 65   3% Er noninventive 99 Pigment 66   1% Dy noninventive 91 Pigment 67   1% Nd noninventive 95 Pigment 68   1% Eu noninventive 93 Pigment 69   1% Pr noninventive 92 Pigment 70   1% La noninventive 94 Pigment 71   1% Ce noninventive 95

CONCLUSION

It is apparent from Table 1 that all the inventive pigments have elevated colour strengths compared to the noninventive pigments. This means that the inventive pigments, based on equal starting weights, attain higher optical densities than the noninventive pigments. 

What is claimed is:
 1. Metal azo pigments comprising: a) at least two metal azo compounds which differ at least in the type of metal and which each contain structural units of the formula (I), or the tautomeric forms thereof,

in which R¹ and R² are each independently OK NH₂ or NHR⁵, R³ and R⁴ are each independently ═O or ═NR⁵, R⁵ is hydrogen or alkyl, and Ni²⁺ metal ions and one or more metal ions Me¹, where Me¹ is a metal ion selected from the group consisting of La³⁺, Ce³⁺, Pr³⁺, Nd²⁺, Sm²⁺, Sm³⁺, Eu²⁺, Eu³⁺, Gd³⁺, Tb³⁺, Dy³⁺, Ho³⁺, Er³⁺, Tm³⁺, Yb²⁺ and Yb³⁺, with the proviso that the amount of Ni²⁺ metal ions and metal ions from the Me¹ group together is 95 to 100 mol, based on one mole of all metal ions in the metal azo pigment, and a molar ratio of Ni²⁺ metal ions to Me¹ metal ions in the metal azo pigment is 1:1 to 4:1, and b) at least one compound of the formula (II)

in which R⁶ is hydrogen or alkyl.
 2. The metal azo pigments according to claim 1, wherein: the molar ratio of M²⁺ metal ions to Me¹ metal ions in the metal azo pigment is 2:1 to 4:1; R⁵ is hydrogen or C₁-C₄alkyl; and R⁶ is hydrogen or C₁-C₄-alkyl or C₁-C₄-alkyl mono- or polysubstituted by OH.
 3. The metal azo pigments according to claim 2, wherein: R¹ and R² are OH, R³ and R⁴ are ═O, R⁶ is hydrogen, components a) and components b) are present together in the form of adducts; the at least one Me¹ salt is selected from the group consisting of La³⁺, Ce³⁺, Pr³⁺, Nd³⁺, Sm³⁺, Tb³⁺ and Ho³⁺ salts; the amount of Ni²⁺ ions and metal ions from the Me¹ group is 100 mol %, based on one mole of all metal ions; the molar ratio of M²⁺ metal ions to Me¹ metal ions is 2.3:1 to 3:1; 1.0 to 2.0 mol of compounds of the formula (II) is present per mole of structural units of the formula (I); and the pigments have a specific surface area of 90 to 150 m²/g.
 4. The metal azo pigments according to claim 1, wherein components a) and components b) are present together in the form of adducts.
 5. The metal azo pigments according to claim 1, wherein: R¹ and R² are OH, R³ and R⁴ are ═O, and, R⁶ is hydrogen.
 6. The metal azo pigments according to claim 1, wherein the metal azo compounds further comprise one or more metal ions Me², where Me² is a metal ion selected from the group consisting of Me²⁺, Ca⁺, Sr²⁺, Ba²⁺, Sc₃₊, Y³⁺, Ti²⁺, Ti³⁺, Zr²⁺, Zr³⁺, V²⁺, Nb³⁺, Cr³⁺, Mo²⁺, Mo²⁺, Mn²⁺, Fe²⁺, Fe³⁺, Co²⁺, Co³⁺, Cu²⁺, Zn²⁺, Cd²⁺, Al³⁺ and Pb²⁺, and the amount of Me² metal ions is less than or equal to 5 mol %, based on one mole of all metal ions in the metal azo pigment.
 7. The metal azo pigments according to claim 1, wherein: the amount of Ni²⁺ ions and Me¹ metal ions is 100 mol %, based on one mole of all metal ions; and the molar ratio of Ni²⁺ metal ions to Me¹ metal ions is 2.3:1 to 3:1.
 8. The metal azo pigments according to claim 1, wherein 0.05 to 4 mol of compounds of the formula (II) is present per mole of structural units of the formula (I).
 9. The metal azo pigments according to claim 1, wherein the pigments have a specific surface area of 20 to 200 m²/g.
 10. A process for producing the metal azo pigments according to claim 1, the process comprising contacting: a compound of the formula (III), or tautomers thereof,

in which X is an alkali metal ion, R¹ and R² are each independently OH, NH₂ or NHR⁵, R³ and R⁴ are each independently ═O or ═NR⁵, and R⁵ is hydrogen or alkyl, with at least one compound of the formula (II)

in which R⁵ is hydrogen or alkyl, simultaneously or successively with at least one nickel salt and at least one Me¹ salt from the group consisting of the di- or trivalent La³⁺, Ce³⁺, Pr³⁺, Nd²⁺, Sm²⁺, Sm³⁺, Eu²⁺, Eu³⁺, Gd³⁺, Tb³⁺, Dy³⁺, Ho³⁺, Er³⁺, Tm³⁺, Yb²⁺ and Yb³⁺ salts, where 0.5 to 0.8 mol of the at least one nickel salt, 0.2 to 0.5 mol of the at least one Me¹ salt are used per mole of compound of the formula (III), and where the sum total of the molar amounts of the metal salts used together is one mole.
 11. The process according to claim 10, wherein: X is a sodium or potassium ion; R⁵ is hydrogen or C₁-C₄alkyl; R⁶ is hydrogen or C₁-C₄alkyl or C₁-C₄-alkyl mono- or polysubstituted by OH, and the at least one Me¹ salt is selected from the group consisting of La³⁺, Ce³⁺, Pr³⁺, Nd³⁺, Sm³⁺, Tb³⁺ and He³⁺ salts.
 12. The process according to claim 10, wherein the metal salts further comprise one or more Me² salts from the group consisting of the Sr²⁺, Fe²⁺, Fe³⁺, Co²⁺, Co³⁺, Cu²⁺, Zn²⁺ and Al³⁺ salts, and the process further comprises contacting the compounds of the formula (III) or tautomers thereof, and the at least one compound of the formula (II) simultaneously or successively with additionally the Me² salts, where less than or equal to 0.05 mol of the at least one Me² salt are used per mole of compound of the formula (III), and the sum total of the molar amounts of the metal salts used together is one mole.
 13. A pigment preparation comprising: the at least one metal azo pigment according to claim 1, at least one auxiliary and/or additive selected from the group consisting of surface-active agents, surface-covering agents, bases and solvents, and optionally at least one further pigment.
 14. The pigment preparation according to claim 13, wherein the pigment preparation comprises the at least one further pigment, and the at least one further pigment comprises C.I. Pigment Green 36 and/or C.I. Pigment Green
 58. 15. A process for producing a pigment preparation comprising the at least one metal azo pigment according to claim 1, the process comprising mixing and/or grinding the at least one metal azo pigment with: at least one auxiliary and/or additive selected from the group consisting of surface-active agents, surface-covering agents, bases and solvents, and optionally at least one further pigment.
 16. A colour filter, photoresist, printing ink, or liquid-crystal display comprising the at least one metal azo pigment according to claim
 1. 17. The colour filter, photoresist, printing ink, or liquid-crystal display of claim 16, wherein the at least one metal azo pigment is a component of a pigment preparation comprising: the at least one metal azo pigment at least one auxiliary and/or additive selected from the group consisting of surface-active agents, surface-covering agents, bases and solvents, and optionally at least one further pigment.
 18. A photoresist comprising: the at least one metal azo pigment according to claim 1, one or more photocurable monomers, one or more reaction photoinitiators, and optionally one or more binders or dispersants and/or solvents.
 19. The photoresist of claim 18, wherein the at least one metal azo pigment is a component of a pigment preparation comprising: the at least one metal azo pigment, at least one auxiliary and/or additive selected from the group consisting of surface-active agents, surface-covering agents, bases and solvents, and optionally at least one further pigment.
 20. A process for producing colour filters for liquid-crystal displays, the process comprising: a) applying the photoresist according to claim 18 to a substrate, b) exposing the photoresist by means of a photomask, c) curing, and d) developing to provide a finished coloured colour filter. 